The present invention relates to a method of electrolytically collecting lead from ashes which are produced in the smelting of lead scrap, lead slug, the pole plates of exhausted storage batteries, etc., in a smelting furnace such as a reverberating furnace, revolving furnace or vertical furnace.
Generally, these ashes are in the form of impalpable powder and contain lead compounds such as lead sulfide, lead oxide and lead sulfate. Elements such as antimony, arsenic, zinc, copper and tin are also contained in minute quantities in the form of simple substances or compounds. The ashes are assumed to be formed by the volatilization of lead or lead compounds occurring in a high-temperature atmosphere within the furnace. The lead content of these ashes amounts to about 70% or more by weight in dry measure. To make full use of resources, therefore, efficient collection of lead from the ashes is a mtter of great importance.
Various methods of treating the ashes have been proposed. As a typical one of the conventional methods, the ashes are mixed with lead ore, lead scrap, lead slug, or the pole plates of exhausted storage batteries or, in the alternative, the ashes are granulated and blended with a solvent, after which they are repeatedly smelted. Although these conventional methods do not require any complicated operation, the collection efficiency is extremely low and requires treating of waste gas and slag so as not to cause pollution problems.